Motor vehicle accessory drive system of various types are known in the art. Most commonly used are drive systems which utilize pulleys and belts to transfer power from the primary power source to the accessories. Also known are systems which utilize friction wheels. However the systems using belts and pulleys are cumbersome and occupy a considerable amount of volume due to the clearance required for the belts and accessory support brackets. This is a particular problem in automobiles where engine compartment space is limited. Additionally, the belt driven systems are inoperative if the belt should break which is a frequent occurrence with these systems.
The systems which utilize friction wheels for the power transfer, through hypothetically superior to the belt driven systems, are not considered practical to those skilled in the art as they are subject to wear which makes frequent readjustment of the contact between the friction wheels necessary. For example, U.S. Pat. No. 4,709,587 issued to Fiornascente discloses a system for driving the accessories of a motor vehicle through the use of friction wheels of a particular design. However, the Fiornascente patent does not disclose a method for adjusting the contact between the friction wheels, a method for compensating for the inevitable wear of the friction wheels nor does it disclose a method for preventing damage to the friction wheels or to the power source should a foreign object traverse the friction wheels contact point. With systems utilizing friction wheels, as in the belt driven systems the potential placement of the accessories is another consideration, especially in front-wheel drive vehicles which have a shortage of available engine compartment space. The present invention solves the aforementioned problems existing with the prior known accessory drive systems.